Method and apparatus for paging in machine to machine or mobile assisted deployments

ABSTRACT

A method and apparatus may be used to perform WTRU-WTRU paging in wireless communications. For example, a wireless transmit/receive unit (WTRU) may be configured to page another WTRU. In this example, the paging WTRU may receive a first message that indicates a group identification (ID). The WTRU may receive a second message that may include an indicator that indicates one or more other WTRUs that the paging WTRU may page. If the received indicator matches a paging indicator of the paging WTRU, the paging WTRU may transmit an access signal to one or more other WTRUs. The paging indicator of the paging WTRU may be predetermined, and may be received in a configuration message from a base station (BS). The first message may be a secondary advanced (SA)-preamble.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/347,424 filed Jan. 10, 2012, which issued as U.S. Pat. No. 8,644,864on Feb. 4, 2014, which claims the benefit of U.S. ProvisionalApplication Ser. No. 61/431,413 filed on Jan. 10, 2011, and U.S.Provisional Application No. 61/524,948 filed on Aug. 18, 2011, thecontents of which are hereby incorporated by reference.

BACKGROUND

Machine to machine (M2M) or machine type (MTC) communications may beused synonymously, and may be defined as communications initiated by themachine, to communicate with either other machines or with humans.Applicable network topologies may include wireless transmit/receive unit(WTRU)-WTRU direct communications which may be used for coverageextension. WTRU-WTRU direct communications may be referred to aspeer-to-peer communications. These communications may be used toincrease network robustness by providing an alternative path forconnectivity.

In typical cellular protocols, a WTRU that is either in idle,disconnected or dormant state, may monitor the base station (BS) orrelay station (RS) infrequently to determine if the WTRU needs to listenfor a data transmission. This process may be referred to as paging. Inorder to minimize battery consumption and increase range, paging signalsmay be designed to be short.

M2M networks as defined above may differ from typical cellular networksin two ways. First, some subscribers may not be configured to decode, ormay be out of range of BS or RS transmissions. These subscribers,however, must still be reached. Second, the number of subscribers in thecell could be very large.

Typical M2M networks do not support paging for a group of subscriberstations. Accordingly, it would be desirable to have a method andapparatus to support paging for group subscriber stations in M2Mnetworks. It would also be desirable to extend the page to a WTRU thatis out of the range of the BS or RS. It would also be desirable toreduce the relative overhead created by MAC messaging for small amountsof data at a time. This overhead may be, along with other signaling,associated with paging.

SUMMARY

A method and apparatus may be used to perform WTRU-WTRU paging inwireless communications. For example, a wireless transmit/receive unit(WTRU) may be configured to page another WTRU. In this example, thepaging WTRU may receive a first message that indicates a groupidentification (ID). The WTRU may receive a second message that mayinclude an indicator that indicates one or more other WTRUs that thepaging WTRU may page. If the received indicator matches a pagingindicator of the paging WTRU, the paging WTRU may transmit an accesssignal to one or more other WTRUs. The paging indicator of the pagingWTRU may be predetermined, and may be received in a configurationmessage from a base station (BS). The first message may be a secondaryadvanced (SA)-preamble.

A WTRU may be configured to receive a page from another WTRU. Forexample, the paged WTRU may detect one or more of its assigned pagingindicators and transmit a message to one or more other WTRUs. The one ormore other WTRUs may belong to a group, and the transmitted message mayindicate the group. The one or more assigned paging indicators may havebeen assigned by a BS at an earlier time via a configuration message.The paged WTRU may use a transmit power ramp up procedure for thetransmitted message until a response is received.

In response to the transmitted message, the paged WTRU may receive anACK from one or more other WTRUs. The ACK may be a group-based ACK. TheACK may be followed by a plurality of messages associated with a WTRU(WTRU-specific messages). The plurality of WTRU-specific messages mayeach include an indicator that indicates a WTRU ID. The paged WTRU maychoose to associate with one of the responding WTRUs. The choice may bebased on a received indicator. The paged WTRU may transmit a networkaccess signal, and may include an indicator that indicates the chosenWTRU ID.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1A is a system diagram of an example communications system in whichone or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram of an example wireless transmit/receive unit(WTRU) that may be used within the communications system illustrated inFIG. 1A;

FIG. 1C is a system diagram of an example radio access network and anexample core network that may be used within the communications systemillustrated in FIG. 1A;

FIG. 2 is a flow diagram of an example method for performing individualpaging with a known WTRU location;

FIG. 3 is a flow diagram of an example method for reducing overhead ingroup paging;

FIG. 4 is a flow diagram of example WTRU discovery procedure;

FIG. 5 is a flow diagram of a paging example for a unicast connection;

FIGS. 6A and 6B are flow diagrams of another example paging procedure

FIG. 7 is a diagram of an example paging method for use in a WTRU; and

FIG. 8 is a diagram of another example group paging method.

DETAILED DESCRIPTION

When referred to hereafter, the terminology “wireless transmit/receiveunit (WTRU)” may include but is not limited to a user equipment (UE), amobile station (MS), and advanced mobile station (AMS), high reliability(HR)-MS, a fixed or mobile subscriber unit, a pager, a cellulartelephone, a personal digital assistant (PDA), a computer, or any othertype of user device capable of operating in a wireless environment. AWTRU may be a non-infrastructure node. When referred to hereafter, theterminology “seeking WTRU” includes but is not limited to a WTRUattempting to discover and associate with peers. When referred tohereafter, the terminology “discoverable WTRU” includes but is notlimited to a WTRU that may be discovered by the seeking WTRU.

When referred to hereafter, the terminology “base station (BS)” mayinclude but is not limited to a Node-B, an advanced base station (ABS),an HR-BS, a site controller, an access point (AP), or any other type ofinterfacing device capable of operating in a wireless environment.

FIG. 1A shows an example communications system 100 in which one or moredisclosed embodiments may be implemented. The communications system 100may be a multiple access system that provides content, such as voice,data, video, messaging, broadcast, and the like, to multiple wirelessusers. The communications system 100 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications systems100 may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrierFDMA (SC-FDMA), and the like.

As shown in FIG. 1A, the communications system 100 may include WTRUs 102a, 102 b, 102 c, 102 d, a radio access network (RAN) 104, a core network106, a public switched telephone network (PSTN) 108, the Internet 110,and other networks 112, though it will be appreciated that the disclosedembodiments contemplate any number of WTRUs, base stations (BSs),networks, and/or network elements. Each of the WTRUs 102 a, 102 b, 102c, 102 d may be any type of device configured to operate and/orcommunicate in a wireless environment. By way of example, the WTRUs 102a, 102 b, 102 c, 102 d may be configured to transmit and/or receivewireless signals and may include user equipment (UE), a mobile station,a fixed or mobile subscriber unit, a pager, a cellular telephone, apersonal digital assistant (PDA), a smartphone, a laptop, a netbook, apersonal computer, a wireless sensor, consumer electronics, and thelike.

The communications systems 100 may also include a base station 114 a anda base station 114 b. Each of the base stations 114 a, 114 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to one or morecommunication networks, such as the core network 106, the Internet 110,and/or the other networks 112. By way of example, the base stations 114a, 114 b may be a base transceiver station (BTS), a Node-B, an evolvedNode-B (eNB), a Home Node-B (HNB), a Home eNB (HeNB), a site controller,an access point (AP), a wireless router, and the like. While the basestations 114 a, 114 b are each depicted as a single element, it will beappreciated that the base stations 114 a, 114 b may include any numberof interconnected base stations and/or network elements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, and the like. The base station 114 a and/or the base station 114b may be configured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The cell may further be divided into cell sectors. For example,the cell associated with the base station 114 a may be divided intothree sectors. Thus, in one embodiment, the base station 114 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 114 a may employ multiple-inputmultiple-output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link, (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, and thelike). The air interface 116 may be established using any suitable radioaccess technology (RAT). Each of WTRUs 102 a, 102 b, 102 c, and 102 dmay be configured to page one or more other WTRUs using paging messages119.

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as universal mobiletelecommunications system (UMTS) terrestrial radio access (UTRA), whichmay establish the air interface 116 using wideband CDMA (WCDMA). WCDMAmay include communication protocols such as high-speed packet access(HSPA) and/or evolved HSPA (HSPA+). HSPA may include high-speed downlink(DL) packet access (HSDPA) and/or high-speed uplink (UL) packet access(HSUPA).

In another embodiment, the base station 114 a and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as evolved UTRA (E-UTRA),which may establish the air interface 116 using long term evolution(LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.16 (i.e.,worldwide interoperability for microwave access (WiMAX)), CDMA2000,CDMA2000 1X, CDMA2000 evolution-data optimized (EV-DO), Interim Standard2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856(IS-856), global system for mobile communications (GSM), enhanced datarates for GSM evolution (EDGE), GSM/EDGE RAN (GERAN), and the like.

The base station 114 b in FIG. 1A may be a wireless router, HNB, HeNB,or AP, for example, and may utilize any suitable RAT for facilitatingwireless connectivity in a localized area, such as a place of business,a home, a vehicle, a campus, and the like. In one embodiment, the basestation 114 b and the WTRUs 102 c, 102 d may implement a radiotechnology such as IEEE 802.11 to establish a wireless local areanetwork (WLAN). In another embodiment, the base station 114 b and theWTRUs 102 c, 102 d may implement a radio technology such as IEEE 802.15to establish a wireless personal area network (WPAN). In yet anotherembodiment, the base station 114 b and the WTRUs 102 c, 102 d mayutilize a cellular-based RAT, (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A,and the like), to establish a picocell or femtocell. As shown in FIG.1A, the base station 114 b may have a direct connection to the Internet110. Thus, the base station 114 b may not be required to access theInternet 110 via the core network 106.

The RAN 104 may be in communication with the core network 106, which maybe any type of network configured to provide voice, data, applications,and/or voice over Internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. For example, the core network 106may provide call control, billing services, mobile location-basedservices, prepaid calling, Internet connectivity, video distribution,and the like, and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1A, it will be appreciatedthat the RAN 104 and/or the core network 106 may be in direct orindirect communication with other RANs that employ the same RAT as theRAN 104 or a different RAT. For example, in addition to being connectedto the RAN 104, which may be utilizing an E-UTRA radio technology, thecore network 106 may also be in communication with another RAN (notshown) employing a GSM radio technology.

The core network 106 may also serve as a gateway for the WTRUs 102 a,102 b, 102 c, 102 d to access the PSTN 108, the Internet 110, and/orother networks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) andthe Internet protocol (IP) in the TCP/IP suite. The networks 112 mayinclude wired or wireless communications networks owned and/or operatedby other service providers. For example, the networks 112 may includeanother core network connected to one or more RANs, which may employ thesame RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, i.e., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 102 c shown in FIG. 1A may be configured tocommunicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B shows an example WTRU 102 that may be used within thecommunications system 100 shown in FIG. 1A. As shown in FIG. 1B, theWTRU 102 may include a processor 118, a transceiver 120, atransmit/receive element, (e.g., an antenna), 122, a speaker/microphone124, a keypad 126, a display/touchpad 128, a non-removable memory 130, aremovable memory 132, a power source 134, a global positioning system(GPS) chipset 136, and peripherals 138. It will be appreciated that theWTRU 102 may include any sub-combination of the foregoing elements whileremaining consistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), amicroprocessor, one or more microprocessors in association with a DSPcore, a controller, a microcontroller, an application specificintegrated circuit (ASIC), a field programmable gate array (FPGA)circuit, an integrated circuit (IC), a state machine, and the like. Theprocessor 118 may perform signal coding, data processing, power control,input/output processing, and/or any other functionality that enables theWTRU 102 to operate in a wireless environment. The processor 118 may becoupled to the transceiver 120, which may be coupled to thetransmit/receive element 122. While FIG. 1B depicts the processor 118and the transceiver 120 as separate components, the processor 118 andthe transceiver 120 may be integrated together in an electronic packageor chip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In another embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and receive both RF and light signals. The transmit/receiveelement 122 may be configured to transmit and/or receive any combinationof wireless signals.

In addition, although the transmit/receive element 122 is depicted inFIG. 1B as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. More specifically, the WTRU 102 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 102 mayinclude two or more transmit/receive elements 122, (e.g., multipleantennas), for transmitting and receiving wireless signals over the airinterface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),and the like), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station, (e.g., base stations 114 a, 114 b), and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. The WTRU 102 may acquire location informationby way of any suitable location-determination method while remainingconsistent with an embodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 1C shows an example RAN 104 and an example core network 106 thatmay be used within the communications system 100 shown in FIG. 1A. TheRAN 104 may be an access service network (ASN) that employs IEEE 802.16radio technology to communicate with the WTRUs 102 a, 102 b, 102 c overthe air interface 116.

As shown in FIG. 1C, the RAN 104 may include base stations 140 a, 140 b,140 c, and an ASN gateway 142, though it will be appreciated that theRAN 104 may include any number of base stations and ASN gateways whileremaining consistent with an embodiment. The base stations 140 a, 140 b,140 c may each be associated with a particular cell (not shown) in theRAN 104 and may each include one or more transceivers for communicatingwith the WTRUs 102 a, 102 b, 102 c over the air interface 116. In oneembodiment, the base stations 140 a, 140 b, 140 c may implement MIMOtechnology. Thus, the base station 140 a, for example, may use multipleantennas to transmit wireless signals to, and receive wireless signalsfrom, the WTRU 102 a. The base stations 140 a, 140 b, 140 c may alsoprovide mobility management functions, such as handoff triggering,tunnel establishment, radio resource management, traffic classification,quality of service (QoS) policy enforcement, and the like. The ASNgateway 142 may serve as a traffic aggregation point and may beresponsible for paging, caching of subscriber profiles, routing to thecore network 106, and the like.

The air interface 116 between the WTRUs 102 a, 102 b, 102 c and the RAN104 may implement the IEEE 802.16 specification. In addition, each ofthe WTRUs 102 a, 102 b, 102 c may establish a logical interface (notshown) with the core network 106. The logical interface between theWTRUs 102 a, 102 b, 102 c and the core network 106 may be used forauthentication, authorization, IP host configuration management, and/ormobility management. Each of WTRUs 102 a, 102 b, and 102 c, may beconfigured to page one or more other WTRUs using paging messages 119.

The communication link between each of the base stations 140 a, 140 b,140 c may include protocols for facilitating WTRU handovers and thetransfer of data between base stations. The communication link betweenthe base stations 140 a, 140 b, 140 c and the ASN gateway 142 mayinclude protocols for facilitating mobility management based on mobilityevents associated with each of the WTRUs 102 a, 102 b, 102 c.

As shown in FIG. 1C, the RAN 104 may be connected to the core network106. The communication link between the RAN 104 and the core network 106may include protocols for facilitating data transfer and mobilitymanagement capabilities, for example. The core network 106 may include amobile IP home agent (MIP-HA) 144, an authentication, authorization,accounting (AAA) server 146, and a gateway 148. While each of theforegoing elements are depicted as part of the core network 106, it willbe appreciated that any one of these elements may be owned and/oroperated by an entity other than the core network operator.

The MIP-HA 144 may be responsible for IP address management, and mayenable the WTRUs 102 a, 102 b, 102 c to roam between different ASNsand/or different core networks. The MIP-HA 144 may provide the WTRUs 102a, 102 b, 102 c with access to packet-switched networks, such as theInternet 110, to facilitate communications between the WTRUs 102 a, 102b, 102 c and IP-enabled devices. The AAA server 146 may be responsiblefor user authentication and for supporting user services. The gateway148 may facilitate interworking with other networks. For example, thegateway 148 may provide the WTRUs 102 a, 102 b, 102 c with access tocircuit-switched networks, such as the PSTN 108, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and traditionalland-line communications devices. In addition, the gateway 148 mayprovide the WTRUs 102 a, 102 b, 102 c with access to the networks 112,which may include other wired or wireless networks that are owned and/oroperated by other service providers.

Although not shown in FIG. 1C, it will be appreciated that the RAN 104may be connected to other ASNs and the core network 106 may be connectedto other core networks. The communication link between the RAN 104 theother ASNs may include protocols for coordinating the mobility of theWTRUs 102 a, 102 b, 102 c between the RAN 104 and the other ASNs. Thecommunication link between the core network 106 and the other corenetworks may include protocols for facilitating interworking betweenhome core networks and visited core networks.

Various non-traditional applications for cellular networks may beconsidered that involve communications not initiated by humans and/ormay not be strictly hierarchical topologies, such as machine-to-machine(M2M) communications or machine type communications (MTC). The M2Mcommunications or MTC may be defined as communications initiated by amachine to communicate with either other machines or humans. The methodsdescribed herein may be applicable to MTC communications, as well asother types of communications.

Network topologies which include WTRU-to-WTRU direct communications maybe used for coverage extension, throughput improvement, and the like.These network topologies may also significantly increase networkrobustness by providing an alternative path for connectivity, bydiscovering nodes when necessary. However, the WTRUs may not be mobileat all, or have a very low mobility.

Changes to the traditional behavior of a WTRU with respect to the way itdiscovers and establishes a link with the network may be necessary,including the functionality of node discovery, routing, association andbandwidth request, as appropriate. A WTRU, possibly assisted by thenetwork, may identify and maintain an association with a set of otherWTRUs to either assist in relaying data to/from the network, orcommunicate data locally without data flows to/from a BS. Clientcollaboration, relaying and WTRU-to-WTRU communication with or without anetwork may be implemented in any type of wireless communication systemsincluding, but not limited to, IEEE 802.16 and any amendments thereof,long term evolution (LTE), universal mobile telecommunication system(UMTS), and the like.

In an 802.16m example, it may be assumed that the WTRU has associatedwith the network prior to paging. In this example, the WTRU may enter anIDLE state before it receives paging parameters. Paging may use aderegistration indicator (DI). The paging function may be updated in aranging procedure using a Ranging Response (RNG-RSP) medium accesscontrol (MAC) message.

Paging may be performed using a two sided grouping. For example, a BSmay be assigned to one or more groups, and a WTRU may be assigned tomultiple groups. The number of groups may be limited to 4. Differentpaging cycles and/or offsets may be used within a group. One of the WTRUgroups may be designated as a primary group. The primary group may havepreference for detection, and may, for example have the smallest offset.Paging may be performed using primary and secondary groups, and theremay be no need to coordinate busy times. A location update procedure maybe triggered if there is no group present.

During paging unavailable intervals, the BS may not expect to be able topage the WTRU. The WTRU may use this time for battery savings or formaking measurements. A re-synchronization and detection of superframeheader (SFH) may be performed towards the end of a period to extract asuperframe number to determine a paging time. New paging parameters maybe signaled using an AAI-DREG-RSP message during an IDLE mode initiationand an AAI-RNG-RSP during a location update.

A broadcast paging message, for example, an AAI-PAG-ADV message, may beused to indicate the presence of DL traffic. The broadcast pagingmessage may be used to poll for a location update, such as in ranging.The broadcast paging message may include an emergency alert. MultipleWTRUs may be identified in the broadcast paging message, therefore atrue group may not exist. A paging message without a WTRU ID mayindicate that the WTRU return to a sleep state. The broadcast pagingmessage may be transmitted, for example, within a frame includingdefined by N_(superframe) module PAGING_CYCLE==PAGING_OFFSET. Thelocation within the frame may be signaled in an A-field map (A-MAP) IE,and may continue in the next frame. Paging by barred cells may beallowed, however network entry may be restricted to preferred BSs.

Operation during a paging listening interval may be based on a pagingcycle and/or offset. Listening may be performed on a per superframebasis. The WTRU may synchronize on a PA-preamble and may decode aprimary SFH (P-SFH). Paging ID information (PGID-Info) may betransmitted regardless of the presence of paging to any WTRU, and maysignal which paging groups are supported by the BS. The PGID-Info may betransmitted at a predetermined location in the listening interval.

Machine to machine communications may involve a large number of devices,where some, but not all devices may be of low or no mobility. Datatransmission may be infrequent and may tolerate relatively high latency.M2M devices may share the network with other types of devices.

Page groups may be used for the following reasons. Due to devicemobility, device location may never be certain. Several BSs in the samearea may be grouped together to cover the uncertainty. As M2M mobilitymay be fairly low, the need for large groups of BSs (and therefore alarge group of WTRUs) may be reduced, but not eliminated. The WTRU maybelong to several groups to support services with different latencyrequirements.

It may be assumed that there are a very large number of devices for eachsector. Most of these devices, however, may be directly associated withthe BS. Only a minority may need to be relayed by another WTRU. Theaverage number of WTRUs that may need to be paged by any other WTRU istherefore small, however it is possible that some WTRUs may need to pagemore than one WTRU. In 802.16, for example, paging a WTRU may berepresented by its Deregistration Information (DI). The DI for the WTRUmay be 18 bits, for example. Paging as a whole, however, may requiremany more bits since paging within a few WTRUs require a large overhead.Note that while each paging WTRU may page only a few other WTRUs, therecould potentially be many paging WTRUs in the cell. If paging isperformed often, the impact of the overhead may be significant.

M2M cases may present the need to page a group of users, for example,devices of a similar type may be paged at the same time for a specifictask. Due to the possibility of some device mobility, a long pagingwindow and small coverage of a paging WTRU, there may be someuncertainty in the paging WTRU, for example, the WTRU may have changedlocation since a previous data exchange.

In one example of a Public Protection and Disaster Relief (PPDR) case,the WTRUs are not associated unless they need to communicate, and theymay never be in an IDLE state. In this case, there is no need forpaging. In another PPDR case, the WTRU may be associated with many otherWTRUs, even when not in active communication, and paging may be used.

In an example for throughput enhancement, all the WTRUs may beassociated directly with the BS and may be paged by the BS. In M2Mapplications, three types of paging may be considered: 1) individualpaging with a known WTRU location, 2) group paging, and 3) individualpaging with an unknown WTRU location. Individual paging may be used forpaging a specific WTRU for a specific purpose. The attachment point ofthe WTRU to the network may be known to a high degree of accuracy.Accordingly, the location of the WTRU may be assumed to have not changedsignificantly from the time of last communication with it. If the WTRUwas recently directly attached to a BS, then it may now be in theservice area of a small enough group of base stations adjacent to theoriginal. If the WTRU was recently attached through a paging WTRU, thenit may now be within range of a small group of WTRUs adjacent to it.

Group paging may be used for paging a group of WTRUs to perform aspecific function. Examples of a specific function may include, 1)network access of a group of WTRUs, for example, in order to performfurther communications, 2) ranging for a location update, and 3)reception of data in broadcast mode, for example in Smart Gridapplications, some or all smart meters may be paged at the same time toprovide new operational parameters.

Individual paging with an unknown location may be used when the locationof the WTRU is not known. There may be several mechanisms to performthat function, for example, a paged WTRU may be instructed to range fora location update. As a result, the location of the WTRU may be known,and the BS may use the opportunity to transmit data to the WTRU.Alternatively, a paged WTRU may be instructed to enter the network.

Paging may be performed on a group or on an individual basis. Paging maybe transmitted from an individual BS or from a group of BSs. Paging mayalso be transmitted from an individual paging WTRU or from a group ofpaging WTRUs. The latter may increase the detection probability, and mayovercome the location uncertainty of the paged WTRU. A cause may beembedded in the paging signal, and may provide an efficient signalingmechanism. If paging is used to indicate a broadcast transmission, thenthe information required to access the broadcast transmission may beincluded in the paging signal.

For the following examples, it may be assumed that the paged WTRU hasmaintained or re-acquired downlink (DL) synchronization, and has updatedits system information sufficiently to decode paging messages orwaveforms. FIG. 2 is a flow diagram of an example method 200 forperforming individual paging with a known WTRU location by extending thetransmission of a paging signal to reach a WTRU that cannot decode theBS transmissions. In this example, the paged WTRU may or may not need toimplement a new procedure in order to be paged by the paging WTRU.

Referring to FIG. 2, any WTRU, whether or not it has any WTRU associatedwith it, may receive 210 a message that indicates to the WTRU to act asa paging WTRU. The paging WTRU may be assigned a WTRU ID that indicatesone or more paging groups for its paging function. These groups may ormay not be the same as the paging groups used for its normal operationas a WTRU. The WTRU ID may indicate a single WTRU to page. A paged WTRUmay be assigned one or more groups that may or may not be the same asthe paging WTRU groups. The assignment may be made during an originalassociation or at any other time. Periodicity and time offset may alsobe assigned during that time.

Paging messages to these paging groups may be transmitted at a knownperiodicity and time offset. The paging WTRU may receive a pagingmessage 215, and if the paging message indicates a previously assignedWTRU ID 220 the paging WTRU may transmit a paging message to the WTRU asindicated by the received WTRU ID 230. Note that the received messagemay include multiple WTRU IDs, and the paging WTRU may transmit a pagingmessage to each of the WTRUs indicated by the received WTRU IDs. If thereceived message does not indicate an assigned WTRU ID, the paging WTRUmay continue to listen for a paging message 240.

A forwarding WTRU may have a WTRU attached to it. If a paging WTRU isalso a forwarding WTRU, the attached WTRUs may be considered pagedWTRUs. A mapping may be defined between the paging WTRU groups and thepaged WTRU groups. The groups used for the paging message may bedetermined by this group mapping. A paging WTRU may be assignedresources and transmit by the BS power for its paging message.

In a multi-point transmission paging example, multiple paging WTRUs maybe assigned at least one common paging group and one or more WTRU IDs topage. If, in addition, the same resources are assigned and the pagingWTRUs are sufficiently synchronized, this example method may result inthe transmission of the same waveform from multiple sources to increasethe probability of paging success. BS paging messages may be CRCprotected to prevent erroneous decoding if multiple WTRU transmitdissimilar information. Neither paging nor paged WTRU may be aware ofthe multi-point transmission.

Joint transmission of pages by multiple WTRUs may provide diversitygains over a single point transmission. Joint transmission of pages bymultiple BSs may also provide diversity gains over a single pointtransmission. If joint transmission is performed by WTRUs along with theBSs, additional performance gains may be achieved. These diversity gainsmay combat short term fast multi-path fading as well as longer termshadow fading. If multiple WTRUs are used to transmit paginginformation, synchronization may be achieved by triggering the BS pagingmessage to the paging WTRU.

Group paging may be performed by indicating a WTRU ID, by transmitting aderegistration identifier (DI), transmitting a group identifier (ID), orusing WTRU IDs that may be separate from the DI and may be assigned bythe network. As a result, it may not be necessary for the paged orpaging WTRU to know whether an individual or a group are paged.

In the examples above, a group paging message may be transmitted for atleast every single paged WTRU. Due to the uncertainty in WTRU locationand the short range of WTRU-WTRU communications, the group pagingmessage may need to be transmitted by many paging WTRUs. It may bepossible to group WTRUs to be paged by location, however since groupingmay be used for different services, group management may becomedifficult.

In order to reduce overhead in group paging, transmission of a group IDmay be limited to the paging WTRU. Reception of the group ID by thepaged WTRU may result in the WTRU transmitting a response signal with apossible transmit power ramp up procedure. Reception of the responsesignal by the paging WTRU may trigger the transmission of a full pagingmessage.

FIG. 3 is a flow diagram of an example method 300 for reducing overheadin group paging. Referring to FIG. 3, the BS may transmit a preamble toestablish a time reference 310. Establishing a time reference may becombined with network synchronization. In one example, a waveformsimilar to an 802.16m primary advanced preamble (PA-preamble) may betransmitted to establish network time and frequency synchronization. ThePA-Preamble may define the superframe and its location within thesuperframe may be pre-determined and known.

A signal similar to an 802.16m secondary advanced preamble (SA-preamble)may be used to transmit a paging group indicator 320 using a selectionof code and time/frequency resources. This may be possible as theSA-preamble, aside from being bandwidth dependent, may have a signaturethat may denote an ID. Reception of the SA-preamble may require aninitial time synchronization obtained from the PA-preamble.

The timing of transmission of the SA-preamble used to convey paging maybe fixed. Alternatively, the timing may be established duringassociation or broadcast. The SA-preamble may be transmitted to a pagedWTRU. The SA-preamble or another signal with similar capabilities mayinclude information related to the type of paging device, for example apaging WTRU, and/or paging group information. The paging group may beindicated in the SA-preamble signature and timing element. The paginggroup may be expressed as a superframe offset relative to the superframeperiodicity. A paging group indicator may be transmitted by any pagingWTRU that has received a paging message, for one of the paged WTRUs ofthe group. The BS may arrange the paging messages such that the adjacentpaging WTRU may transmit the same paging indicator at the same time.

The paged WTRU, in response to the paging message, may then transmit asignal indicating at least its presence. The paging WTRU may listen forthe response signal during an initial listening phase 330. During theinitial listening phase, listening resources may be known and may eitherbe fixed or established during an initial association or by broadcast.The nature of the listening resources may depend on the information andwaveform used. For example, the waveform may be a time domain waveform.In this example, the listening resources may listen during one or morelistening time windows at times relative to the paging indicatorsuperframe. Note that in this example, the added interference caused bythe absence of a paged WTRU may be minimal.

The network in general, or the discoverable peer subscriber station(DPSS), also known here as the paging WTRU, may not know at this pointthat a paged WTRU is within range. The paging WTRU may obtaininformation regarding a paged WTRU that is within range. In addition,the paging WTRU may obtain a path loss estimate.

In order to minimize interference, the paged WTRU may start transmissionat a low power. The paged WTRU may determine whether transmit powerramping will be used 340. If the paged WTRU determines that transmitpower ramping will be used, the paged WTRU may perform an initialtransmit power ramping 350.

To perform initial transmit power ramping, the paged WTRU may transmit awaveform to make itself known to the paging WTRU. In an example ofmulti-point transmission, the paged WTRU may transmit a waveform tomultiple paging WTRUs. For example, 802.16m ranging preambles for eithersynchronized (S-RNG) or non-synchronized devices (NS-RNG) may be used.The paging WTRU may receive a paging response signal (PRS) from a pagedWTRU 360, that may ramp up its transmission power during a listeningwindow 370. The paged WTRU may ramp up its transmission power until aresponse is received or an allowed maximum is reached, in which case thetransmit power ramping has failed. The initial power level and thetransmit power ramping steps may be predetermined. The listening windowsmay be designed such that the paging WTRU knows how many transmit powerramping steps have occurred. With knowledge of the step size an initialpower, the paging WTRU may estimate the path loss between itself and thepaged WTRU 380. The paging WTRU may then transmit a paging message usinga power based on the estimated path loss 390.

If the paged WTRU determines that transmit power ramping will not beused, the paged WTRU may use a fixed power that may be known to alldevices 395. In this example, the PRS resources may be provided in termsof the paging indicator or time reference. For example, fixed resourcesmay be used every n'th frame starting at a predetermined time after thepaging indicator.

Not all paging WTRUs that have received the PRS are required to respond.Determining which paging WTRU responds may be based on informationestimated either in a distributed manner or under direct BS control. Forexample, the paging-paged WTRU path loss estimate or other criterion maybe used to determine the best paging WTRU. Note that the determinationis not unique, and may result in more than one best paging WTRU.

In a centralized control mode, all the paging WTRUs that have receivedthe PRS may send the path loss estimate information or other informationto the BS. The BS may then decide which paging WTRU should respond basedon the path loss estimate and other parameters, for example,capabilities of the forwarding WTRU and its own traffic load.

In one alternative, the responding paging WTRU may be determined by theBS in a distributed manner by predetermining a threshold on a functionof the WTRU-BS and WTRU-WTRU path loss, and/or or other criterion. Thefunction may be signaled by the BS, hard wired, or unspecified. Trafficload may be taking into account in a similar manner, for example, by athreshold on buffer occupancy.

Note that in itself the procedure does not absolutely guarantee that atleast one WTRU will respond. A high degree of certainty may be achievedby BS control in the following manner. Every WTRU that has received aPRS may signal that indication to the BS. The BS may also know if theWTRU has responded and may adjust the threshold as necessary.Transmission power for the paging WTRU may be determined from the pathloss estimate obtained above. The response of the paging WTRU maycontain the paging messages, for example, as detailed in embodimentsabove.

In a WTRU/BS coordinated paging example, the BS may initially attempt todirectly page the paged WTRU. If a response is not received within aspecified time interval, the assistance of one or more paging WTRUs maybe requested. Requesting the assistance of one or more paging WTRUs mayimprove the reliability of paging while minimizing the battery drainimpact on the paging WTRU. Note that in this example, the attachmentpoint may be either the BS or the paging WTRU. The protocol of whichnode initiates the first attempt, for example the WTRU, may be eitherestablished in advance as part of a network association or signaled tothe paging WTRU by the BS at any other time. In this example, it is notassumed that the paged WTRU may not be able to receive pages from theBS. It may be assumed, however, that there may be a non-trivialprobability of success. The probability of success may not be highenough to provide the desired reliability of successful paging.

An example autonomous paging WTRU triggering may be used in conjunctionwith the WTRU/BS coordinated paging example to reduce the signalingoverhead. The paging WTRU may monitor the medium for paging responses tothe BS pages. If no response is signaled, the WTRU may autonomouslyinitiate assistance to the BS paging. While this may be autonomous, itmay be coordinated with the BS in advance either at a network attachmenttime or any other time. While this example may reduce the signalingoverhead, it may require that the paging WTRU be made aware of andmonitor the common channel that may be used for paging responsemessages. This monitoring may offset the battery consumption advantageof the WTRU/BS coordinated paging example.

Reduced overhead multi-point paging may be used in conjunction with, forexample, 802.16n discovery procedures. Multi-point paging may be usedwhen one or more WTRUs are out of the coverage area of the BS, and theyare moving in the cell such that there is some uncertainty regardingwhich associated WTRU may best page them.

Paging for a unicast connection may be performed using the followingexample WTRU discovery procedure shown in FIG. 4. FIG. 4 shows aplurality of associated WTRUs 410-430, and one non-associated WTRU 440.One or more associated WTRUs may be designated as discoverable. Thesediscoverable WTRUs may transmit preambles that contain informationregarding network timing, bandwidth, one or more WTRU group IDs, and thetype of device or its ownership, if applicable. The discoverable WTRUsmay transmit a single preamble or a pair of primary and secondarypreambles.

Referring to FIG. 4, WTRU 430 may transmit a preamble 445 and networkconnection information (NCI), using known resources or resources derivedfrom the cell-ID in the SA-preamble for the NCI. The transmitted NCI maycontain parameters required for initial access. The parameters mayinclude, for example, resources, codes, etc. In this procedure, alldiscoverable WTRUs that are members of a group may transmit the samepreamble and NCI on the same resources. This may result in the pagedWTRU transmitting a group response to all WTRUs which have transmittedtheir ID as explained below.

The non-associated WTRU 440 may derive ranging parameters from the NCI.Alternatively, if the NCI is not used, the non-associated WTRU 440 mayderive the ranging parameters 450 from the WTRU ID or group WTRU ID, asindicated by the preamble. The non-associated WTRU 440 may transmit anaccess signal 455 and ramp up its transmit power 460. The code forranging may be specified in the NCI.

An associated WTRU, for example WTRU 430, may be designated as a pagingWTRU, and may receive the access signal 455. If the received accesssignal 455 matches the access parameters of the paging WTRU 430 andcrosses a threshold, the paging WTRU 430 may respond with an ACK 465.Upon receiving the ACK 465, the non-associated WTRU 440 may stoptransmit power ramping 470. The paging WTRU 430 may transmit a specificNCI 475 that includes specific access parameters. The non-associatedWTRU 440 may then access one or more of the responding associated WTRUs.

FIG. 5 is a flow diagram of a paging example 500 for a unicastconnection. The cell shown in FIG. 5 includes a BS 510, a WTRU 520, anda WTRU 530. The WTRU 520 may be referred to as a paging WTRU, and theWTRU 530 may be referred to as a paged WTRU. In this example, WTRU 520and WTRU 530 belong to group 1 540. Group 1 540 is shown with two WTRUsfor simplicity, and it is understood that each group may include morethan two WTRUs. It is also understood that each cell may include morethan one BS.

Referring to FIG. 5, the BS 510 may transmit a paging ID message 550 toone or more WTRUs. In this example, the BS 510 is transmitting thepaging ID message 550 to WTRU 520. The paging ID message 550 may includethe contents of a paging indication information element (IE). The pagingID message 550 may also include a one or more paged WTRU IDs, one ormore paged group IDs, and/or for example, a Synchronized ranging channel(S-RCH) resource indicator. The paging ID message 550 may include anassigned paging indicator (PI) for a single IDLE state WTRU or a groupof IDLE state WTRUs. One or more PIs may be assigned to each WTRU. AWTRU in an IDLE state may be assigned a wakeup pattern that may matchthe preamble or NCI epochs of a discoverable WTRU.

In response to receiving the paging ID message 550, the WTRU 520 maytransmit a paging indicator IE 560 to WTRU 530. One or more WTRUs may beinstructed to transmit a paging indicator IE 560 that indicates that anassociated WTRU or group of WTRUs is paged. The paging indicator IE 560may be embedded in an NCI message. Alternatively, the NCI message mayindicate the resources where a separate paging indicator message (PIM)may be found. The paging indicator IE 560 may include a group preamble,a group NCI, and/or a group paging indicator message, and may betransmitted using a procedure similar to the discovery procedure above.

Each paging indicator or group of paging indicators may have a codegroup associated with it from which a ranging code may be selectedrandomly. If this group is distinct from those used for initial networkentry, then it may indicate to the paging WTRU that the access is aresponse to a page. It may also indicate the group to which the pagedWTRU belongs.

Since all the members of a discoverable group may transmit the same NCI,they may transmit the same PIM on the same resources, therefore pagingthe same WTRU. Alternatively, in a group that uses a separate PIM, somediscoverable WTRUs may be instructed to omit this message. If themessage is omitted, then no other transmission may occur on the sameresources.

Referring again to FIG. 5, in response to the paging indicator IE 560,the WTRU 530 may transmit an access signal 570 via an S-RCH resource.The access signal 570 may be a ranging preamble transmitted using atransmit power ramp up procedure. The WTRU 520, in response, maytransmit an acknowledgement (ACK) 580 and a WTRU-specific SA-preambleand NCI 585. The WTRU 530 may then transmit an additional access signal590 and follow the normal cell access procedure.

FIGS. 6A and 6B are flow diagrams of another example paging procedure600. Referring to FIG. 6A, a BS 610 may assign a PI and/or a wakeuppattern to each IDLE state WTRU 620, 630 in the cell. The PI may referto a single WTRU or a group of WTRUs. One or more PIs may be assigned toeach WTRU. The assigned wakeup patterns may match the preamble and/orNCI epochs of a discoverable WTRU. The PI may also indicate that a WTRUis designated as a paging WTRU.

Referring to FIG. 6B, WTRU 620 may be designated as a paging WTRU. Thepaging WTRU 620 may transmit a group preamble, a group NCI, and/or agroup PIM 640 to the paged WTRU 630. The paging WTRU 620 may use adistinct code group to limit the number of WTRU responses. The pagedWTRU 630 may be in an idle state, and may listen 650 for paginginformation embedded in the NCI or PIM. If the paged WTRU 630 receives apaging indicator that was assigned to it, the paged WTRU 630 maytransmit an access signal 660 for network entry. If a code group isassociated with the PIM, the paged WTRU 630 may select a code from theassociated code group. In response, the paging WTRU 620 may transmit apreamble associated with a WTRU (WTRU-specific preamble) and NCI 670 tothe paged WTRU 630.

Paging indicators may be included in the WTRU-specific NCI. In addition,if a PIM is used, paging indicators may be added to the PIM. The pagingindicators may include an ID associated with a WTRU that indicates, to apaging WTRU, which WTRU to page. Each paging indicator may include oneor more IDs associated with one or more WTRUs, respectively. The pagingindicators may also belong to a group or may be specific to a pagedWTRU. The paging indicators may be different than those used in thepreliminary stage. Any ID that may have been assigned to a WTRU when itwas previously connected and retained by the network may be used as apaging ID. An idle state WTRU may see a paging indicator assigned to itand continue the network access procedure, including its ID in theaccess message as normally used when answering a page.

FIG. 7 is a diagram of an example paging method 700 for use in a WTRU.The WTRU may receive a configuration message 710 from the BS indicatingthat the WTRU is designated as a paging WTRU. The paging WTRU maytransmit a group preamble, a group NCI, and/or a group PIM 720. Thepaging WTRU may listen for an access signal 730. If an access signal isreceived, the paging WTRU may transmit a WTRU-specific preamble, NCI,and/or a PIM 740. The paging WTRU may then initiate a network accessprocedure 750 and continue to transmit a group preamble, a group NCI,and/or a group PIM 720. If an access signal is not received, the pagingWTRU may continue to transmit a group preamble, a group NCI, and/or agroup PIM 720.

The examples above may allow increased flexibility in the pagingprocess. For example, discoverable WTRUs may be grouped by a combinationof their service characteristics and rough geographical location in thecell, such as groups that correspond to a contiguous fraction of a cellarea. As a result, the BS may base the size of the paging area in thecell based on its uncertainty regarding the location of the paged WTRU.

The paged WTRUs may be grouped based on one or a combination of theirservice characteristics and location. For example, all the WTRUs thatprovide a certain service may belong to a group and may be paged so thatthey may receive a message. How the location information is used may bedetermined by the BS. If the WTRU density is below a threshold, thewhole group in a certain geographical area may be polled. Otherwise, ifthe density is over a threshold, then sub-groups may be set up such thatthe paged WTRUs are dispersed throughout the cell to prevent overloadingforwarding WTRUs with access attempts.

A two-stage procedure may be used with different paging groups. Thistwo-stage procedure may be used in conjunction with code use toprioritize between accesses from different code groups.

FIG. 8 is a diagram of another example group paging method 800. Thewireless communication system shown in FIG. 8 includes a plurality ofWTRUs associated with a BS, and a non-associated WTRU, WTRU G 810. TheBS is not shown for simplicity. Of the associated WTRUs, WTRU A 801,WTRU B 803, and WTRU C 805 belong to a first group, for example, Group1, and WTRU D 802, WTRU E 804, and WTRU F 806 belong to a second group,for example, Group 2.

Referring to FIG. 8, the WTRUs that belong to Group 1 may each transmita PA-preamble 821, an SA-preamble 823, and an NCI 825. The SA-preamble823 may include a group ID 827 that indicates which group the WTRUbelongs, for example, Group 1. The group ID 827 may be based on servicecharacteristics. The NCI 825 may include paging indicators 829, orindicate where a separate paging indicator may be transmitted, forexample, the paging indicator may be transmitted in a separate message.The NCI 825 may also be group-based and include a group ID.

The WTRUs that belong to Group 2 may each transmit a PA-preamble 831, anSA-preamble 833, and an NCI 835. The SA-preamble 833 may include a groupID 837 that indicates which group the WTRU belongs, for example, Group2. The group ID 837 may be based on service characteristics. The NCI 835may include paging indicators 839, or indicate where a separate pagingindicator may be transmitted, for example, the paging indicator may betransmitted in a separate message. The NCI 835 may also be group-basedand include a group ID.

The non-associated WTRU, WTRU G 810, may detect one or more of itspaging indicators and transmit a ranging preamble 840 to a group of itschoice, for example, Group 2. The one or more paging indicators may havebeen assigned by a BS at an earlier time via a configuration message.The ranging preamble 840 may include an indicator 845 or a field thatindicates the chosen group. In this example, the chosen group may beGroup 2. WTRU G 810 may continue to transmit the ranging preamble 840using a transmit power ramp up procedure until a response is received.Due to the transmit power ramping, associated WTRUs that are nearby maytend to respond first.

In this example, WTRU E 804 and WTRU F 806 may respond first with agroup-based acknowledgement (ACK) 850 that may include an indicator 852that indicates the WTRU group, for example, Group 2. The group-based ACK850 may be followed by a PA preamble associated with a WTRU(WTRU-specific PA-preamble) 851, 853, an SA-preamble associated with aWTRU (WTRU-specific SA-preamble) 854, 856, and an NCI associated with aWTRU (WTRU-specific NCI) 855, 857. The WTRU-specific SA preamble 854,856 may include an indicator that indicates a WTRU ID 861, 863, forexample, WTRUs E and F, respectively. The WTRU-specific NCI 855, 857 mayinclude an indicator that indicates a WTRU ID 862, 864, for example,WTRUs E and F, respectively.

The non-associated WTRU G 810 may transmit a new network access signal870, for example a ranging preamble. The network access signal 870 maybe transmitted on resources determined from the NCI 857, and may includean indicator 875 that indicates the chosen WTRU ID 864. At this point, anormal access procedure may be followed.

The examples shown in FIGS. 5-8 may be modified to indicate the start oravailability of a multicast transmission. In this multi-point pagingprocedure, the paging indicators may be mapped to multicast channeldescriptors. The mapping may be established during a previous connectedstate. The paging indicators may be embedded in the NCI or a separatemessage indicated by the NCI. Alternatively, the multicast channeldescriptors may be explicitly transmitted and may be either embedded inan NCI or in a separate message. A WTRU that receives a paging indicatorfor its multicast service or multicast channel descriptors may beginreceiving multicast transmission.

In some cases, the number of paged and paging WTRUs may be low, and thelatency requirements may be tight. To accommodate these cases, theexamples in FIGS. 5-8 may be adapted to perform single point paging. Inan example single point paging procedure, the discoverable WTRU maytransmit locally individual preambles and NCI. A non-associated WTRU mayaccess an associated WTRU using signaled ranging parameters. This may bea single stage approach similar to BS access by a WTRU. The NCI and PIMmessages may be used to indicate paging in this example.

An example transmission of NCI may include PIM transmission. In thisexample, NCI partitioning may be performed. The NCI may be divided intotwo subpackets, for example, an Initial Network ConfigurationInformation (I-NCI) and a Supplemental Network Configuration Information(S-NCI).

The I-NCI may be transmitted first, with its location determinable fromthe SA-preamble index, (Idx), and subcarrier set index, (n) of theSA-preamble transmitted by the forwarding WTRU. An example of thecontent of the I-NCI is shown in Table 1. An example of the content ofthe S-NCI is shown in Table 2. The location of the S-NCI may bespecified in the I-NCI.

TABLE 1 Example for I-NCI contents and format Size Syntax (bits) NotesBS IDcell 10  Frame Configuration 6 The mapping between value of thisindex Index and frame configuration is listed in Table 806, Table 807,and Table 808 If (WirelessMAN-OFDMA True if Frame configuration index isequal with to FDM-based UL PUSC 5, 7, 9, 11, 13, 15, 20, 21, 22, 23, 24,25, Zone 26, 27, 28, 29 or 30 for 5/10 MHz channel Support){ bandwidthaccording to Table 806; 4, 6, 8 or 10 for 8.75 MHz channel bandwidthaccording to Table 807; 3 or 5 (with CP = ⅛) for 7 MHz channel bandwidthaccording to Table 808. False if Frame configuration index is somethingelse UL_Permbase 7 May indicate UL_Permbase used in WirelessMAN-OFDMAsystem with FDM- based UL PUSC Zone. Reserved for example, 1 to round upto integer bytes }else{ USAC 5/4/3 May indicate the number of subbandsK_(SB) For 2048 FFT size, 5 bits For 1024 FFT size, 4 bits For 512 FFTsize, 3 bits UFPC 4/3/3 May indicate the frequency partitionconfiguration For 2048 FFT size, 4 bits For 1024 FFT size, 3 bits For512 FFT size, 3 bits UFPSC 3/2/1 May indicate the number of subbandsallocated to FPi (i > 0) in 16.3.7.2.3 For 2048 FFT size, 3 bits For1024 FFT size, 2 bits For 512 FFT size, 1 bits UCAS_(SB0) 5/4/3 Mayindicate the number of subband-based CRUs in FP0 in 16.3.7.3.1 For 2048FFT size, 5 bits For 1024 FFT size, 4 bits For 512 FFT size, 3 bitsUCAS_(MB0) 5/4/3 May indicate the number of miniband-based CRUs in FP0in 16.3.7.3.1 For 2048 FFT size, 5 bits For 1024 FFT size, 4 bits For512 FFT size, 3 bits Resource Index for S-NCI for example, 6 Reservedrounding to integer bytes, for example }

TABLE 2 Contents and format for S-NCI Size Syntax (bits) Notes If(Support of WirelessMANOFDMA with FDM-based UL PUSC Zone){ Subframeoffset of the RCH 2 May indicate the subframe offset (O_(SF)) of the RCHallocation. The range of values may be 0 ≦ O_(SF) ≦ 3 Start RP codeinformation 4 May indicate the k_(ns), which may be the of the parameterfor start of the RP code group RCH (r_(ns0)). r_(ns0)(k_(ns)) = 16 ×k_(ns) + 1, k_(ns) = 0, 1, . . . , 15 Number of RP codes 2 May indicatethe number of RP codes and allocated for coverage the particular codesthat may be used for extension ranging ranging with the forwarding WTRU.}else{ Subframe offset of the S- 2 May indicate the subframe offset(O_(SF)) of RCH the S-RCH allocation Start RP code information Mayindicate the ks that may be the of the parameter controlling the startroot index S-RCH of the RP codes (r_(s0)). r_(s0) = 6 × k_(s) + 1 Therange of values may be 0 ≦ k_(s) ≦ 15 Transmission timing offset 3Indicates N_(RTO), which may be the of SRCH parameter used for thecalculation of the sample number, T_(RTO), which may be applied toadvance the ranging signal transmission timing relative to the defineduplink transmission timing point based on the frame structure from WTRUperspective when WTRU conducts initial or handover ranging in afemtocell. T_(RTO) = floor(N_(RTO) × (T_(g) − 2) × Fs)(samples) whereN_(RTO) = min(RTD/(T_(g) − 2), 7), and RTD may be the round trip delayfrom the femto-BS to the overlay macro-BS. The range of values is 0 ≦N_(RTO) ≦ 7. } UCASi 3/2/1 May Indicate the number of total allocatedCRUs, in a unit of a subband, for FPi (i ≧ 0) in 16.3.7.3.1 For 2048 FFTsize, 3 bits For 1024 FFT size, 2 bits For 512 FFT size, 1 bitsForwarding EIRP 5 Unsigned integer from 1 to 31 in units of 1 dBm, where0b00000 = 1 dBm and 0b11111 = 31 dBm. WTRU Transmit Power 5 Unsigned5-bit integer. May specify the Limitation Level maximum allowed WTRUtransmit power. Values may indicate power levels in 1 dB steps startingfrom 0 dBm. EIRxPIR,min 5 Unsigned integer from −133 to −102 in units of1 dBm, where 0b00000 = −133 dBm and 0b11111 = −102 dBm. Pre-access S-NCIIndicator 1 May indicate whether this is a pre-access S-NCI that may beused for Group Discovery mode 0b0: not a pre-access S-NCI 0b1:pre-access S-NCI Resource Index for PIM for example, 6

The I-NCI may be transmitted in the N_(I-NCI) Distributed LogicalResource Units (DLRUs) in the first subframe of a superframe. Theparticular resource index may be determinable from the SA-preambletransmitted by the forwarding WTRU. Within the selected subframe, theI-NCI may occupy the last 5 OFDM symbols, therefore effectively forminga Type-3 subframe.

An resource allocation for the S-NCI may be defined in the I-NCI, asshown in Table 1, and the allocation may depend on the IDCell and theframe configuration of the serving BS/RS. Paging indicators may beincluded in the I-NCI, the S-NCI, or in a separate PIM message. Thelocation of the PIM may be indicated in the I-NCI or in the S-NCI.Tables 1 and 2 show an example in which the location is advertised inthe S-NCI. In this example, specific code groups may be assigned to eachPI.

Table 3 illustrates an example format for a PIM message.

TABLE 3 Contents and format for PIM Size Syntax (bits) Notes N_PI forMay indicate the number example, 8 of distinct paging indicators in thismessage  For (i=0; i<N_PI; i++)  { PI for Paging indicator example, 16Start RP code 4 May indicate the ks information of the that may be theparameter S-RCH controlling the start root index of the RP codes(r_(s0)). r_(s0) = 6 × k_(s) + 1 The range of values may be 0 ≦ k_(s) ≦15 }

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

What is claimed is:
 1. A wireless transmit/receive unit (WTRU)comprising: a receiver configured to receive, from at least one secondWTRU, a message that includes a paging indicator (PI); and a transmitterconfigured to, on a condition that the received PI includes an IDassociated with the WTRU, transmit a ranging preamble to the at leastone second WTRU.
 2. The WTRU of claim 1, wherein the ranging preambleincludes a group ID associated with the at least one second WTRU.
 3. TheWTRU of claim 1, wherein the receiver is further configured to receive aconfiguration message that indicates the PI associated with the WTRU. 4.The WTRU of claim 1, wherein the transmitter is further configured totransmit the ranging preamble using a transmit power ramping procedure.5. The WTRU of claim 1, wherein the receiver is further configured toreceive an NCI message from the at least one second WTRU, wherein theNCI message includes a WTRU ID associated with a transmitting WTRU. 6.The WTRU of claim 5, wherein the transmitter is further configured totransmit, to the WTRU associated with the WTRU ID, a second rangingpreamble in response to the received NCI message.
 7. The WTRU of claim6, wherein the second ranging preamble indicates the WTRU ID associatedwith the transmitting WTRU.
 8. A method for use in a wirelesstransmit/receive unit (WTRU), the method comprising: receiving a messagefrom at least one second WTRU, wherein the message includes a pagingindicator (PI); and transmitting, on a condition that the received PIincludes an ID associated with the WTRU, a ranging preamble to the atleast one second WTRU.
 9. The method of claim 8, wherein the rangingpreamble includes a group ID associated with the at least one secondWTRU.
 10. The method of claim 8 further comprising: receiving aconfiguration message that indicates the PI associated with the WTRU.11. The method of claim 8, wherein the ranging preamble is transmittedusing a transmit power ramping procedure.
 12. The method of claim 8further comprising: receiving an NCI message from the at least onesecond WTRU, wherein the NCI message includes a WTRU ID associated witha transmitting WTRU.
 13. The method of claim 12 further comprising:transmitting, to the WTRU associated with the WTRU ID, a second rangingpreamble in response to receiving the NCI message.
 14. The method ofclaim 13, wherein the second ranging preamble indicates the WTRU IDassociated with the transmitting WTRU.
 15. A wireless transmit/receiveunit (WTRU) comprising: a transmitter configured to transmit a messagethat includes a paging indicator (PI); and a receiver configured toreceive a ranging preamble, wherein the ranging preamble includes agroup ID associated with the WTRU.
 16. The WTRU of claim 15, wherein thetransmitter is further configured to transmit an NCI message, whereinthe NCI message includes a WTRU ID associated with the WTRU.
 17. TheWTRU of claim 15, wherein the receiver is further configured to receivea second ranging preamble in response to the NCI message.
 18. The WTRUof claim 17, wherein the second ranging preamble indicates the WTRU IDassociated with the WTRU.